Tox: dextromethorphan, benadryl

Question 1

Brief description of dextromethorphan

Answer 1

Found in many OTC cough meds. Recreationally abused.

Related to levorphanol (synthetic opioid agonist)

Question 2

MOA dextromethorphan tox

Answer 2

NMDA antagonist, inhibits serotonin uptake.

At high doses, opioid receptor agonist

Question 3

Symptoms of dextromethorphan toxicity

Answer 3

Agitation, ataxia, nystagmus, visual/auditory hallucinations.
Severe overdose: coma, respiratory depression.
Serotonin syndrome rare but may occur if ingested with other serotonergic agents.

Question 4

Mechanism of benadryl toxicity (receptors targeted/effects)

Answer 4

1) H1 antagonist -> SMC relaxation, sedation
2) Muscarinic antagonist -> anticholinergic SE
3) Na+ channel blockade -> QRS prolongation, seizures

Question 5

Potential cardiotoxic effects from benadryl

Answer 5

QRS widening, dysrhythmias

Question 6

Tx of benadryl OD

Answer 6

1) benzos for seizures

2) NaHCO3 for QRS widening